[PATCH v3] hwmon: adm1272: Enable temperature sampling for adm1272 adm1278

[Chu Lin <linchuyuan@google.com>]

Problem:
	adm1272 and adm1278 supports temperature sampling. The
current way of enabling it requires the user manually unbind the device
from the driver, flip the temperature sampling control bit and then bind
the device back to the driver. It would be nice if we can control this in a
better way by reading the dt.

Solution:
	Introducing device tree binding analog,temp1-enable. If the
flag is set, flip the temp1_en control bit on probing.

Testing:
1). iotools smbus_write16 35 0x10 0xd4 0x0037 // disable the temp1_en
2). recompile the dt to have  analog,temp1-enable set
3). Probe the driver and make sure tempX shows up in hwmon

Signed-off-by: Chu Lin <linchuyuan@google.com>
---
ChangeLog v1->v2:
 - Rename adm1272-adm1278-temp1-en to analog-temperature1-enable

ChangeLog v2->v3:
 - Rename analog-temperature1-enable analog,temp1-enable

 drivers/hwmon/pmbus/adm1275.c | 36 +++++++++++++++++++++--------------
 1 file changed, 22 insertions(+), 14 deletions(-)

diff --git a/drivers/hwmon/pmbus/adm1275.c b/drivers/hwmon/pmbus/adm1275.c
index 19317575d1c6..0482670281bd 100644
--- a/drivers/hwmon/pmbus/adm1275.c
+++ b/drivers/hwmon/pmbus/adm1275.c
@@ -475,6 +475,7 @@ static int adm1275_probe(struct i2c_client *client,
 	const struct coefficients *coefficients;
 	int vindex = -1, voindex = -1, cindex = -1, pindex = -1;
 	int tindex = -1;
+	bool temp1_en;
 	u32 shunt;
 
 	if (!i2c_check_functionality(client->adapter,
@@ -536,6 +537,9 @@ static int adm1275_probe(struct i2c_client *client,
 	if (shunt == 0)
 		return -EINVAL;
 
+	temp1_en = of_property_read_bool(client->dev.of_node, "analog,temp1-enable") &&
+		(mid->driver_data == adm1272 || mid->driver_data == adm1278);
+
 	data->id = mid->driver_data;
 
 	info = &data->info;
@@ -614,16 +618,18 @@ static int adm1275_probe(struct i2c_client *client,
 		info->func[0] |= PMBUS_HAVE_PIN | PMBUS_HAVE_STATUS_INPUT |
 			PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT;
 
+		ret = config;
+		/* Enable temp if it is instructed by dt (it is disabled by default) */
+		if (temp1_en && !(config & ADM1278_TEMP1_EN))
+			config |= ADM1278_TEMP1_EN;
 		/* Enable VOUT if not enabled (it is disabled by default) */
-		if (!(config & ADM1278_VOUT_EN)) {
+		if (!(config & ADM1278_VOUT_EN))
 			config |= ADM1278_VOUT_EN;
-			ret = i2c_smbus_write_byte_data(client,
-							ADM1275_PMON_CONFIG,
-							config);
+		if (ret != config) {
+			ret = i2c_smbus_write_word_data(client, ADM1275_PMON_CONFIG, config);
 			if (ret < 0) {
-				dev_err(&client->dev,
-					"Failed to enable VOUT monitoring\n");
-				return -ENODEV;
+				dev_err(&client->dev, "Failed to enable config control bits");
+				return ret;
 			}
 		}
 
@@ -685,16 +691,18 @@ static int adm1275_probe(struct i2c_client *client,
 		info->func[0] |= PMBUS_HAVE_PIN | PMBUS_HAVE_STATUS_INPUT |
 			PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT;
 
+		ret = config;
+		/* Enable temp if it is instructed by dt (it is disabled by default) */
+		if (temp1_en && !(config & ADM1278_TEMP1_EN))
+			config |= ADM1278_TEMP1_EN;
 		/* Enable VOUT if not enabled (it is disabled by default) */
-		if (!(config & ADM1278_VOUT_EN)) {
+		if (!(config & ADM1278_VOUT_EN))
 			config |= ADM1278_VOUT_EN;
-			ret = i2c_smbus_write_byte_data(client,
-							ADM1275_PMON_CONFIG,
-							config);
+		if (ret != config) {
+			ret = i2c_smbus_write_word_data(client, ADM1275_PMON_CONFIG, config);
 			if (ret < 0) {
-				dev_err(&client->dev,
-					"Failed to enable VOUT monitoring\n");
-				return -ENODEV;
+				dev_err(&client->dev, "Failed to enable config control bits");
+				return ret;
 			}
 		}
 
-- 
2.28.0.rc0.105.gf9edc3c819-goog